Patients are recruited from those referred to Pediatric Sleep Disorders Clinic for evaluation of clinically suspected OSAS. Patients will be eligible if they have a history of snoring, and have no other medical disease. All patients will undergo an 8-hour overnight sleep study. This is a routine medical care for patients with symptoms of OSAS, and is standard for diagnosis. The patients with adnotonsillar hypertrophy & polysomnography compatible to OSAS will be eligible for the study. Age-matched healthy children from the general population will perform a similar polysomnography to document normal breathing. These children will be recruited from the general population by advertisement.